There has long been a pressing need in the medical, pharmaceutical and veterinary arts for a dispensing system that is capable of administering a beneficial agent at a controlled rate over a prolonged period of time. The need exists for increasing the maximum time of therapeutic effectiveness of beneficial agents, especially for beneficial agents whose maximum time of therapeutic effectiveness, when administered in conventional dosage forms such as a tablet, is only for a few hours. A patient using such a conventional form must take repeated dosages at frequent intervals. Moreover, during intervals between doses the therapeutic level in the blood decreases due to metabolic activities and the level can become so low that it is practically ineffective. Also, as a result of frequent doses, the level of medicine available for therapy will fluctuate between doses. The need for a dispenser exists also for delivering beneficial agents that are difficult to deliver, usually attributable to some physical property. For example, beneficial agents that are insoluble in aqueous fluids are difficult to deliver because they do not form solutions and, accordingly, they cannot be dispensed in solution from a dispensing device. Then, too, many beneficial agents exhibit lipid solubilities and these agents are difficult to deliver by conventional dosage forms.
Additionally, a need exists for a dispensing system for dispensing a beneficial agent to a ruminant animal. Ruminant animals including cattle, sheep, giraffe, deer, goat, bison and camels, and more particularly cattle and sheep, comprise an important group of animals that require periodic administration of beneficial agents and nutrients. The beneficial agents and nutrients are administered for better health and for the treatment and alleviation of various conditions. Ruminants have a complex three or four compartment stomach. The rumen, the largest of the stomach compartments, serves as an important location for receiving and passing beneficial agents and nutrients into other compartments, including the abomasum and the intestine.
Presently ruminants are treated by repeated administrations of agents and nutrients at frequent time intervals. This form of treatment is inconvenient and expensive, and it does not lend itself to good reliable therapy or nutrition. Additionally, agents and nutrients are orally administered in the form of a bolus to ruminants, and this form of administration, like other repeated modes of administration, also does not lend itself to acceptable therapy or nutrition. Moreover, ruminants regurgitate what they swallow, they chew their cuds, and they spit out conventional boluses quickly after administration thereof.
There is therefore, in view of the above presentations, a pressing need for a dispensing system for use with ruminants that will, after a single administration, efficiently administer agents and nutrients over a prolonged period of time. There also is a pressing need for a dispensing system for a prolonged release of an agent or a nutrient at a controlled rate in the rumen, by a dispensing system that is swallowed easily by the ruminant and will remain in the rumen for a long period of time without being regurgitated or otherwise eliminated from the rumen.